The engine may fail to start due to an electrically shorted sensor. Some of the sensors may internally short and not blow any fuses. A technician may find no spark and no operation of the fuel injectors in the diagnosis. One way a technician may isolate the defective sensor is by disconnecting sensors one by one to see if the engine starts.

Misfires under load (acceleration) can be caused by leaky spark plug boots. When a spark plug boot leaks, it allows the spark to arc, or jump, to the cylinder head. If evidence of arcing can be seen on the inside of the spark plug boot, new spark plug wires will be needed.

The engine may fail to start due to an electrically shorted sensor. Some of the sensors may internally short and not blow any fuses. A technician may find no spark and no operation of the fuel injectors in the diagnosis. One way a technician may isolate the defective sensor is by disconnecting sensors one by one to see if the engine starts.

A dirty, or contaminated mass airflow (MAF) sensor can cause the engine to run poorly. There may be a Check Engine Light with trouble codes relating to the MAF sensor, P0102 and/or P0103. In some cases, carefully cleaning the sensor element will fix the problem, but replacement may be required.

If the engine cranks but does not start, it may be caused by a tripped inertia switch. Switch the key to "ON" and the fuel pump should be heard running for a second or two. Listen at the gas filler if necessary. The inertia switch is located on the firewall and can be tripped when the parking brake is set too hard and then released. The inertia switch should be reset, and will click when it is reset.

A dirty, or contaminated mass airflow sensor (MAF) can cause the engine to run poorly. The Check Engine Light may or may not illuminate. MAF sensor related fault codes P0102 and/or P0103 may be stored. In some cases, carefully cleaning the sensor element will fix the problem. If not, replacement of the sensor may be required.

If the engine cranks but will not start, it may be due a failed distributor. In the diagnosis, it may be discovered that the Electronic Engine Control (EEC) Unit is the cause if ignition spark is restored after disconnecting the Spark Output (SPOUT) Connector.

A dirty, or contaminated mass airflow (MAF) sensor can cause the engine to run poorly. There may be a Check Engine Light with trouble codes relating to the MAF sensor. In some cases, carefully cleaning the sensor element will fix the problem, but replacement may be required.

Water intrusion into a connector (X309) located under the cab, beneath the driver's seat, can cause a rough idle, ABS Light and Check Engine Light illumination, and automatic transmission shifting problems. If needed, connector repair parts are available from Mazda dealers, and possibly some Ford dealers.

If the engine will not start after distributor rotor replacement, a common mistake is to install the distributor rotor in the wrong position. The rotor may seat in three positions and one should note the direction before removal.